AUSTIN, Texas (AP) — Texas lawmakers cut $5.4 billion from public schools nearly 18 months ago, and now districts are headed to court to argue that the resulting system is so inefficient and unfair that it violates the state constitution.

Simply restoring funding to levels prior to the 2011 legislative session won’t be enough to fix the fundamentally flawed way Texas funds its schools, lawyers for the districts say. They point out that the cuts have come even as the state requires schools to prepare students for standardized tests that are getting more difficult, and amid a statewide boom in the number of low-income students that are especially costly to educate.

Putting the money back would make things easier, they say.

“That’s not all it’s about, but that would be a start,” said John Turner, an attorney representing about 60 of the school districts suing.

The trial starts Monday in the Austin courtroom of Texas District Judge John Dietz and is expected to last into January. It is the sixth legal battle of its kind since 1984 and involves six lawsuits filed since last October on behalf of about two-thirds of Texas school districts, which in turn educate around 75 percent of the state’s roughly 5 million students.

The largest group of plaintiffs is led by the Fort Bend Independent School District outside Houston but includes districts from Amarillo to Abilene to Austin and most points in between, as well as Dallas, Houston, and San Antonio schools.

Districts both in rich and poor parts of the state are on the same side of the case. Texas’ funding system relies heavily on property taxes and a “Robin Hood” scheme in which districts with high property values or abundant tax revenue from oil or natural gas resources turn over part of the money they raise to poorer districts.

Many “property wealthy” districts say that while they are in better shape than their poorer counterparts, the system still starves them of funding since local voters who would otherwise support property tax increases to bolster funding for their schools refuse to do so, knowing that most of the money would be sent somewhere else.

Also suing are charter schools, who want state funding for their facilities, and a small number of parents.

All argue that the system defies the Texas Constitution, which promises “a general diffusion of knowledge” by an “efficient system of public free schools.”

“Given the fact that the public education system is founded on local control, success or failure of a school district is necessarily linked to the school district’s own leadership, polices and operations,” the office said in pretrial brief. “If a local school district fails to provide its students a general diffusion of knowledge, such a result, while unacceptable, does not render the entire public school system unsuitable.”

Whatever Dietz decides is likely to be appealed to the state Supreme Court. If the courts rule against the state, it will be up to the Legislature to remake the system — but a high-court ruling may not come in time to tackle the issue during next year’s legislative session, said David Thompson, lead attorney for the group of plaintiffs led by the Fort Bend district.

Thompson said “there is no magic bullet” for fixing school finance in Texas, but added, “I would hope, if nothing else, we don’t see additional cuts.”

Abbott’s office stands little chance of prevailing, if history is any guide.

The Texas Supreme Court ruled in 1989 that the school finance system was unconstitutional because students in rich and poor districts alike “must be afforded a substantially equal opportunity to have access to educational funds.” After subsequent overhauls by the Legislature, the high court again found the school finance systems unconstitutional in 1991, 1992 and 2005.

In 2006, the Legislature cut local school property taxes by one-third and aimed to make up for it with state funding from a business margin tax that by some calculations has created a school funding shortfall of $6 billion annually.

Then, looking to plug gaping budget holes last year, the Legislature cut $4 billion in spending for schools and $1.4 billion in grant programs, causing per-student funding to fall more than $500 last year — even while enrollment is increasing by 80,000 students annually. District superintendents say they’ve laid off teachers and increased class sizes to cope with the cuts.

Enrollment growth has been almost entirely fueled by students from low-income families who cost more on average to educate. Last year, more than 60 percent of Texas students qualified for free or reduced-price lunches, and 17 percent of students statewide have limited proficiency in English at best — requiring more spending on bilingual programs.

Meanwhile, the state has introduced a new, more rigorous standardized testing system designed to better prepare students for college. Budget cuts have left less money for schools to spend getting their students ready for them, or providing remedial instruction for those who don’t pass.

“You can’t give us the mission,” Thompson said, “then not give us the tools to accomplish that mission.”